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Author Topic: got the homebrew bug again!  (Read 456 times)
KD8DQK
Member

Posts: 42




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« on: March 29, 2008, 06:24:14 AM »

Ok folks, i've had some pretty decent success with my eggbeater on satellite work (primarily AO-51) and now I have the homebrew bug again. I've built an array designed for satellite work and it should be a good working design. The downlink section is a 12-element yagi optimized for 440 mhz and should have around 4db gain. The uplink is an experimental 5E quad design for 144mhz, and on paper it looks very promising. This will all be mounted on something similar to a camera tripod so I can manually track the birds.

Here's my problem: How do I build a diplexer (NOT a duplexer, there's a difference) to use one feedline for this array? Can a simple unit be built or do I have to buy one? What about auto band switching? I would appreciate any help.

                                                                                                                                                       73,

                                                                                                                                               Jeff/ kd8dqk
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AB2KT
Member

Posts: 62




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« Reply #1 on: April 04, 2008, 02:15:33 AM »

What power will you be running?

In a recent issue of CQ VHF, Kent Britain WA5VJB published a design for a two-fer pair of his cheap yagis arranged Arrow-style, along with a very simple and effective diplexer. IIRC the limit was about 20 W. The diplexer might be exactly what you're looking for.

73
Frank
AB2KT
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KB1GMX
Member

Posts: 762




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« Reply #2 on: April 08, 2008, 04:28:21 PM »

I did a dual band antenna using the Kent Britain Cheap yagi designs.  the result was 3 elements for 2m and 6 elements for 438mhz and excellent gain on both without excessive directivity on the 4438 antenna.  I get good coverage on Ao27, Ao51 and others with it.  I's short
being under 4Ft and light.  As the two antennas are independent and I use to radios (one for RX and one for TX) I used separate feeds. but I have a diplexer if needed as well as a UHF high pass filter as the UHF radio I use has a wide front end and 2M does get into it.

If you check ARRL.net TIS pages there is a Diplexer design there and others around the net.


Allison

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